1. Field of the Invention
The present invention relates to semiconductor switch devices, and more particularly to semiconductor switch devices of the type comprising a thyristor and a transistor in combination.
2. Description of the Prior Art
Prior art power transistors give rise to a large voltage drop in the large current region, resulting in low capacity to withstand a peak surge current. Prior art thyristors also are not very practical in that it is difficult to turn them off through the control electrode and their turn-off means are intricate. Further, with prior art gate turn-off thyristors, it has been difficult to obtain switching element to large current capacity. This is because gate-reverse-biasing at turn-off induces current concentration and hot-spots in a region separated from the gate.